Embodiments of the present invention relate to the registration of an image on a substrate.
An image registration apparatus scans one or more radiation beams on a substrate to register an image on the substrate. The radiation beams are modulated or patterned in accordance with the image to be registered onto the substrate. A typical image registration apparatus comprises a substrate support and radiation beam source, focusing, modulating, and scanning components, to generate and modulate a radiation beam to form an image on the substrate. The substrate may be, for example, a mask blank to be used in the fabrication of semiconductors, and which is exposed to the modulated radiation beam to register an circuit image onto photosensitive material of the mask blank. The mask blank is then developed and stabilized to form a mask to be used in the fabrication of integrated circuits.
It is desirable to increase the image registration speeds to generate high resolution images with good throughput. However, image registration speeds are often limited by the speed of the radiation beam modulators that modulate the intensities of the radiation beams. For example, one commonly used radiation beam modulator is an acousto-optic modulator (AOM) which modulates a radiation beam by constructive and destructive interference of the radiation beam. A typical AOM is capable of modulating about 32 beams at a rate of about 50 MHz and within about 16 grayscale levels to provide an image data processing speed of about 1.6 GHz. While such image data processing speeds are acceptable for conventional image registration methods, faster data throughput is often required to register images having higher levels of complexity and finer line widths.
Thus, it is desirable to have an image registration apparatus and method that provides higher image registration speeds without sacrificing image resolution. It is also desirable to provide the higher data throughput rates consistently and reliably.
In a method of registering an image on a substrate, the substrate is placed on a substrate support and a radiation beam is directed toward the substrate. The radiation beam is reflectively diffracted to modulate the intensity of the radiation beam. The modulated radiation beam is scanned across the substrate to register an image on the substrate.
A method of registering an image on a mask blank comprises placing a mask blank on a substrate support; directing a laser beam toward the mask blank; splitting the laser beam into a plurality of laser beamlets; reflectively diffracting the radiation beamlets to modulate the intensities of the laser beamlets by adjusting a plurality of adjustable reflectors between first and second positions while maintaining a plurality of fixed reflectors at a fixed position; and scanning the modulated laser beamlets across the mask blank to register an image on the mask blank.
A method of registering an image on a mask blank comprises placing a mask blank on a substrate support and moving the substrate support; projecting a laser beam toward the mask blank; splitting the laser beam into a plurality of laser beamlets; modulating the laser beamlets by applying a signal at a modulation frequency of less than about 10 MHz to at least about 160 reflector clusters, each reflector cluster comprising a plurality of fixed and adjustable reflectors that reflectively diffract the laser beamlets, wherein the adjustable reflectors are adjustable between first and second positions and the fixed reflectors are maintained at fixed positions; and scanning the modulated radiation beam across the mask blank to register an image may be registered on the mask blank.